This invention relates to a mount used for connecting two members while isolating and/or controlling the transfer of motion, and particularly motion due to vibration, between these members. Mounts of the general type are described in U.S. Pat. Nos. 3,147,964, 3,642,268, and 3,698,703.
The earlier type of mount disclosed in said U.S. Pat. No. 3,147,964, utilizes primarily the directed energy absorbing characteristics of a rubber-metal interface to impede the transmission of vibration between two members, and also to provide a certain mount of shock isolation in the mounting of one mechanical member to another, while still mechanically connecting the members as desired. These members can be any of a vast variety of devices such as different parts of mechanisms or vehicles, supports for machinery, and packaging supports for large masses. Of particular interset are the connections of chassis power train and body parts in vehicles. For example, the mounting of an engine in an automobile requires control and isolation in six different degrees of freedom, namely motion along X, Y and Z axes and rotation about these axes, i.e. roll, pitch and yaw axes. In this area of application alone, the modern demands for vibration control/isolation and adequate support and anchoring present sophisticated mount design requirements which are aggravated by the need to accomodate some degree of misalignment which is to be expected in mass production systems.
The aforementioned '268 and '703 patents disclose such mounts wherein the vibration isolating effect of a resilient (such as rubber) member coupled between the members is modified by the placement of a damping liquid in cavities located on opposite sides of and within the resilient member. These cavities are connected through a passage which limits the flow of the liquid between the cavities, thus damping the motion of the resilient member along a plane extending through the two cavities.
With respect to such fluid damped mounts, the metal to rubber bonds in those devices are of the post-bonded type, which means that the bond is formed by assembling separate rubber and metal parts, with an adhesive therebetween which is later thermally activated to provide a bond between these parts. Various types of such bonding are discussed in those patents. In many applications of mounts such a bond is not reliable from a physical adhesion standpoint, and may also have discontinuities which alter the desired continuous metal-rubber bond that is needed.
It is also recognized in the art that a good bond between the rigid (e.g. metal) parts in such mounts introduces an impedance mis-match into the mechanical system which is effective in minimizing the transmission of noise or vibration energy across this bond. Each such interface in the path along which vibrational energy can be directed will substantially damp the vibration and provide additional isolating capacity. Thus, it is desirable to maximize the use of such interfaces as much as possible without compromising the over-all mechanical design of a mount.